Looks good to me and yeah the rough looking shell is normal.
That is a good price, cheapest I've seen them here in the states was $700 about 2 years ago. Good luck with him it's just too bad your trying to get rid or the Arm, it would be a pretty awesome display having an Arm and FRT sharing a tank.
in second thought, I might like to try out a combo with the armatus and FRT. I'm just afraid that the FRT might spook the armatus alot and nip on its fins.
i do know that FRT aggressive is generally a hit and miss but usually ends up not the way you want it to be.
Does anyone have experiences with FRTs and fish tankmates?